The invention is based on a vane cell pump, particularly for feeding fuel to fuel injection pumps of internal combustion engines as defined hereinafter.
Such vane cell pumps, of the kind known for instance from U.S. Pat. No. 2,832,199 or German Patent Disclosure DE 40 33 455 A1, are used, among other purposes, also in injection pumps for internal combustion engines, in order to fill the fuel supply chamber of the injection pump with fuel from the fuel tank at supply pressure. From the fuel supply chamber, a metered quantity of fuel is then withdrawn from the injection pump and delivered at very high injection pressure to the various injection nozzles. The vane cell pump is generally integrated into the injection pump and is driven by its drive shaft. Since the drive shaft of the fuel injection pump rotates synchronously with the rpm of the engine, which varies over wide ranges, the vane cell pump produces a variably high feed pressure depending on the rpm. Since the fuel metering in the fuel injection pump is substantially facilitated if the fuel in the fuel supply chamber is at a constant pressure, in the known vane cell pump the fuel supply chamber is connected via a pressure regulating valve to a fuel return line leading to the fuel tank, so that the pressure in the fuel supply chamber is kept at a constant pressure level, regardless of the rpm of the vane cell pump.